MemberDrive.org

DDD distinguishes between 2 types of service objects: 1. Application layer services. Direct/coordinate domain models to perform business operations and coordinate infrastructure tasks with those (such as persistence). 2. Domain layer services. They represent operations that don't belong to a domain entity. They are a kind of domain model, just like domain entities. The Application layer should not implement your business logic. It just coordinates objects in the Domain layer, which are the ones in charge of your business logic. In our case, we don't use (1) because, by using Active Record, the only task left for those Application-level service objects would be to coordinate domain models, which is exactly what our controllers already do. A service object would not add any value, so we don't use those. We do use (2). For example, in the video, the ActivitySpikeDetector or Signup could be considered domain-level service objects. We just don't call them "services" or give them any special treatment. They are just domain objects to us. The problem I see with service objects in our community is that the hardcore proponents almost always advocate organizing your business logic in application-level service objects. This is a complete distortion of the whole idea, and its negative consequences have been documented for well over two decades. I don't really care a whole lot about service objects, believe it or not. My main problem is misinformation and how many newcomers get on the wrong track because someone, probably well-intended but quite ignorant about the matter, tells them that in Rails you can't invoke models from controllers. Well, we do!